211
ACUS01 KWNS 031957
SWODY1
SPC AC 031956

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0256 PM CDT Wed Sep 03 2025

Valid 032000Z - 041200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL PLAINS AND LOWER MISSOURI VALLEY...

...SUMMARY...
Scattered thunderstorms capable of producing large to very large
hail and severe wind gusts should occur this afternoon and evening
across parts of the central Plains and lower Missouri Valley.

...20Z Update...
The general thunderstorm forecast was updated based on observational
trends. The severe probabilities remain unchanged. See the previous
forecast for additional information.

..Wendt.. 09/03/2025

.PREV DISCUSSION... /ISSUED 1128 AM CDT Wed Sep 03 2025/

...Central Plains into the Lower Missouri Valley...
A mid-level shortwave trough over southern SD/eastern NE will
continue to advance quickly southeastward today as a large-scale
upper-level low moves from western ON to near Lake Superior through
the period. The shortwave trough is forecast to reach the lower MO
Valley by late afternoon, with an attendant belt of moderately
strong northwesterly mid/high-level flow overspreading the central
Plains into the mid MS Valley. At the surface, a cold front will
advance southward across parts of the central Plains and lower MO
Valley, with generally low to mid 60s surface dewpoints present
ahead of the boundary. Diurnal heating of this airmass will
contribute to moderate instability (MLCAPE around 1000-2000 J/kg) by
mid afternoon across central/eastern KS, with weaker instability
forecast with eastward extent into MO. As convective inhibition
gradually erodes near the front, scattered thunderstorms will likely
develop along its length from central KS into the lower MO Valley
during the 20-00Z period.

Around 35-55 kt of northwesterly flow in the 500-250 mb layer will
yield similar values of effective bulk shear, which will support
organized updrafts. A few supercells will probably evolve across
central/eastern KS and perhaps into western MO, where the main risk
will be large to very large hail given steep lapse rates aloft and
favorable shear. Severe wind gusts will also be possible with these
supercells, or any small clusters/bowing segments that can develop
where low-level lapse rates are steepest (mainly KS into northwest
OK and parts of the OK/TX Panhandles). Some severe threat should
persist into the evening as multiple small clusters move southward
into southern KS and adjacent portions of far northern OK and
southwest MO, before they eventually weaken as convective inhibition
increases with nocturnal cooling.

...Great Lakes/Midwest...
Additional thunderstorms should develop this afternoon along/near
the cold front across parts of Lower MI into central IL. Poor lapse
rates aloft and limited low-level moisture (reference 12Z soundings
from APX and ILX) will likely temper the degree of instability that
can develop, even with diurnal heating. While occasional
strong/gusty winds appear possible with thunderstorms that spread
east-southeastward this afternoon and evening, the overall severe
threat should remain fairly limited.

$$